Regulator for dynamo-electric machines



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B, THOMSON. REGULATOR FOR DYNIAMO ELECTRIC MACHINES. No. 430,327.Patented June 17. 1890.

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, E. THOMSON. REGULATOR FOR DYNAMO ELECTRIC MACHINES.

No. 430,327. Patented June 17, 1890.

' UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS.

REGULATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 430,327, dated June 17,1890.

Application filed March 8, 1888. Serial No. 266,639. (No model.)

To all whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, and aresident of Lynn, in the county of Essex and State of Massachusetts,have invented a certain new and useful Dynamo Electric Machine, of whichthe following is a specification.

My present invention relates to an improvement in dynamo-electricmachines whereby economy of material is obtained with high output inthose machines which are to be used for constant-current purposes, andespecially in arc-lighting machines.

I apply in my invention a set of demagnetizing or opposing coils aroundthe armature of the machine, as in my Patent No. 333,573, dated January5, 1886, and arrange means for varying thecurrentwhichtraversesthedemagnetizing coil or coils over the armature or for varyingthe number of convolutions through which the current passes at any time.The

object is to cause a great falling off of electro-motive force of thearmature when the current increases slightly above the normal current,as when a fall of resistance occurs in the circuit either suddenly orgradually, or, in other words, the characteristic curve of the machineis made to descend or droop rapidly after a position on the curve ispassed at which the normal current is yielded, or the current will beproduced with an electro-motive force which is falling when the currentincreases and rising when the current decreases from the normal value.

In the accompanying drawings, Figure 1. shows in side elevation adynamo-electric machine with my invention in one of its forms appliedthereto. Fig.2 shows a detail of the apparatus illustrated in Fig.- 1.Fig. 3 illustrates an arrangement in which instead of the singlecontrolling-magnet responsive to the changes of current a series ofmagnets is employed for the purpose of obtaining a more sensitiveaction. Fig. 4 illustrates in detail one of the magnets of Fig. 3. Fig.5 shows an arrangement that might be employed for producing the samechanges in the circuit as are produced by the series of mag nets, Fig.3. Fig. 6 illustrates an equivalent way'of changing the efiect of thedemagnetizing-coils by shunting current variably from them instead of byvarying the number of convolutions through which the current may pass.Fig. 7 is a diagram of the connections of the machines.

In Fig. 1, A indicates the armature of the machine, which armature iswound after the Gramme, Siemens, or other fashion, and is mounted in anysuitable manner for revolvin g between the pole-pieces of a suitablefieldmagnet. The core of the armature contains so much iron as not tobecome saturated magnetically when the machine is at work. Upon thefield-magnets coils F F are wound for magnetizing them strongly-as, forinstance, nearly or quite to saturation. These coils are preferablywound and connected in multiple arc and placed in the main circuit ofthe machine, although other means of getting a strong field, even byshunt field-coils or by separate excitation, may be used. I prefer,however, the disposition shown.

In order to prevent, as far as possible, sudden changes in the magnetismof the field- ,niagnet or sudden fluctuations occurring, I

propose to make the field magnetism the re sultant of the magnetizingeffect of two or more field-magnet coils, which form or are placed inseparate branches or circuits having difierent self-induction. On suddenincrease of current the current will reach its maximum in one coil,after that in the other, owing to this difference of self-induction, andthe disturbance will be distributed in point of time through aninterval, so that the change will be less sudden than if the currentreached its maximum in both of the coils at once. As the field magnetismis the sum of the eifects of the two coils, it is obvious that theeffect of this arrangement willbeto make the change less sudden andmarked than if the fluctuation or sudden increase of current took placein one single field-magnet coil only. The difference of self-inductionin the two coils of branches may be obtained in obvious manner, as bygiving a different number of turns to the coil. The current which passesin the two coils may be made equal by having their resistances equal, orby adding resistance to the coil branch which has the least resistance,as at 0". Over the armature is placed or wound a stationary set of coilsD D, which, when in circuit, convey current in a direction to neutralizeor tend to neutralize the induced magnetism of the armature as producedbythe field-magnets. Itis only requisite that this opposing action havea value such that under any conditions the machine yields its normalcurrent and an electro-motive force just sufficient to maintain thatnormal current. A moving contact-arm V slides over a set ofcontact-pieces connected with the sections or successive turns of thecoils D D, as shown, and this contact-arm V is controlled by a lever II,actuated by a magnetcore I of coil 0 against the counteraction of abalance-weight \V and spring S. The coil 0 is made responsive to thevariation of main current, and may therefore be put into the maincircuit, as shown. The connections are such that when the current in thecircuit of lights L increases above the normal the contact at V isshifted to bring into action the turns of D, traversed by current tooppose the magnetism of the field upon the armature A and cut down theelectro-motive force, and when the current decreases from the normal toincrease the said force by cutting out turns of coils D D. This givesstability of current strength under varied conditions, either with allthe lights in circuit or with a lessened number.

It is obvious that any other form of magnet or any other arrangement ofcontroller magnet and motor mechanism, such as are ordinarily used withelectric regulators, might be employed in place of the magnet shown, andlikewise that the switcharm H might be moved by any other desired means,as by hand.

Fig. 2 simply shows the relation of the coutact-arm V to the contacts.It is well to have it short-circuit a section or a few sections of coilsD Din passing from one point to another to avoid spark.

The arrangement shown in Figs. 3 and a is designed to secure thegreatest possible promptness of action and sensitiveness of thecontrolling main circuit in putting into the circuit the portions of thecoils D of Fig. 1. A series of electro-magnets C C C C" C (L areconnected in series or in parallel in the main circuit, being woundaccordingly, and their independent armatures are independent] y adjustedeach to open a shunt-contact around a section of the coil D when a veryslight departure from normal current takes place, and to close suchshunts on a slight lowering of current. It will of course be understoodthat in this case the retractors for the different armatures aredili'erently adjusted, so that they will be drawn down in succession asthe amount increases from normal, a slightly-greater current beingrequired to bring down each successive armature of the set. Thearmaturcs and magnets are preferably constructed as shown in Fig. 4,though any sensitive arrangement will sutlice. The armature N, Fig. 4,is mounted on a lever with knife-edge pivot-s at P, and has a retractilespring S, delicately poising the armature at normal current in coil C.The 0011- tact K is a shunt around D, a section of coil D, Fig. 1, andthis contact is opened and closed in consequence of slight variations ofcurrent in coil 0. The armature is given a very limited range or play.The action is far more sensitive and prompt than is the case with Fig.1, and under normal conditions a constant play of the armatures andcontacts takes place.

In Fig. 5 the magnet C operates to open a group of shunt-contacts at K Varound sections of coil D, and it may supplant apparatus of Fig. 3. Thecontacts are arranged to open in rapid succession, and notsimultaneously, in which case the magnet C is given by construction asomewhat longer range without variation of pull with a given current.-

The variation of power in coils D may, as indicated in Fig. 6, besecured by varying a shuntresistance R around D by a moving contact V,passing over a succession of fixed contacts, as usual in such cases.This plan is less economical of current energy.

In Fig. 7 the circuit-connections of Fig. 3, taken as a type, aredisplayed in complete form, although they might be variously modified.

IVhat I claim as my invention is 1. The combination, in adynamo-electric machine, of a demagnetizing-coil or set of coils woundover the armature, and means responsive to current changes in thecircuit supplied by the machine for varying the cur rent in or thenumber of turns of said coil or set of coils, as and for the purposedescribed.

2. In a dynamo-electric machine, the combination, with a series ofcontrolling-magnets connected to the circuit of the machine, of ademagnetiZing-coil wound in sections over the armature of the machine,and circuits from said individual sections to switch contactsindividually controlled by the magnets, as and for the purposedescribed.

3. In a dynamo-electric machine, two fieldmagnet coils arranged inseparate branches or circuits having different self-induction, and anartificial resistance in one of said circuits adjusted, as described, soas to distribute the current in a manner to cause the current to bedistributed equally in the two coils.

Signed at Lynn, in the county of Essex and State of Massachusetts, this23d day of February, A. D. 1888.

ELIIIII THOMSON.

Witnesses:

OTIs K. STUART, F. W. WEBSTER.

